In wireless networks employing General Packet Radio Service (GPRS), a coding scheme for data message transmissions is selected by rules embedded in a fixed network and in a mobile station that are designed to result in the highest data throughput with the fewest possible retransmissions. GPRS is an extension of circuit-switched networks and data transmission services that uses packet radio transmissions to carry data messages using protocols such as Internet Protocol (IP) or X.25 information from mobiles to the network and visa versa, in data blocks, or packets. GPRS is an extension to the circuit-switched Global System for Mobile communications (GSM), having four different coding schemes with effective data rates of 9.05, 13.4, 15.6 and 21.4 kilobits per second (code rates ½, ⅔, ¾ and 1) within the data blocks.
Some GPRS-enabled fixed networks can send a command to a mobile station, such as a cell phone, an Internet-enabled mobile phone or a personal digital assistant, to transmit data blocks using a selected one of the four coding scheme. The error rate of the selected coding scheme may rapidly degrade, however, with changing radio conditions or geographical movements of the mobile device. The mobile unit may have limitations in its coding capabilities and its ability to adapt to coding scheme commands. With the move toward third-generation network standards, there are even more possible problems with high-performance networks that use a wider variety of coding schemes. Mobile stations need to adapt their coding schemes rapidly during a data message when possible, and the fixed network needs to recognize mobile stations that are unable to use certain coding schemes, in order to use a best possible coding scheme and avoid undue retransmissions when a coding scheme is selected that cannot be accommodated by a mobile station.
Current GPRS fixed networks use dynamic link adaptation methods that monitor the quality of packet transfers and select one of the four presently defined channel coding schemes (also referred to herein simply as “coding schemes”) based on changing radio conditions. As technologies and protocols emerge and evolve for wireless data transmissions, additional coding schemes will become available. For example, GSM networks incorporating Enhanced Data for Global Evolution (EDGE) with packet-switched enhancements for GPRS have nine additional coding schemes for increased performance. Other wireless network technologies such as GSM/EDGE Radio Access Network (GERAN) and Universal Mobile Telecommunications System (UMTS) provide enhanced coding schemes, requiring network algorithms that can determine the coding scheme adaptability of the mobile station and direct coding scheme commands to the mobile station based on the adaptability. When mobile stations do not respond to all of the defined set of four coding schemes, dynamic link adaptation methods in current use result in sub-optimal data throughput, and in some case, can result in no communication capability with certain mobile stations.